Large-screen projection-type display

Abstract

The object of the invention is to provide a large-screen projection-type display using a transmission-type screen, wherein the transmission-type screen is formed of two or more sheets 4, 7, is tilted toward the viewer's side with a small gap kept between the sheets, and is stable relative to the temperature and moisture change of the environment. The front sheet 4 provided on the viewer's side and the Fresnel sheet 7 provided on the projection source side are tilted forward by about 7° toward the viewers. The springs 10 are extended through wires 9 to exert the tension on the front sheet 4 in the vertical direction. At the same time, the springs exert a pressure on the Fresnel sheet 7 in the vertical direction.

What is claimed is: 
     
       1. A large-screen projection-type display using a transmission-type screen, wherein s id transmission-type screen is formed of, at least, two sheets, or a first sheet provided on the viewer's side, and a second sheet provided on the projection source side far from said first sheet, both of said sheets are tilted toward the viewers by about 0.04 radian or above relative to the vertical direction, said first sheet is tensioned at least in the vertical direction, said second sheet has a warp of more than about 2.4 times as large as its thickness, and said first sheet and said second sheet are kept spaced about 7 mm or below. 
     
     
       2. A large-screen projection-type display according to claim 1, wherein said first sheet has spring means provided at its upper and lower ends so that said tension is applied by said spring means. 
     
     
       3. A large-screen projection-type display according to claim 1, wherein said first sheet has a shelf member provided at least at the lower end, and said tension in said first sheet is applied by exerting the weight of said second sheet on said shelf member. 
     
     
       4. A large-screen projection-type display according to claim 2, wherein said spring means exert not only said tension on said first sheet but also a pressure in the horizontal direction thereon. 
     
     
       5. A large-screen projection-type display according to claim 2, wherein said spring means exert not only said tension on said first sheet but also a pressure on said second sheet in the vertical direction. 
     
     
       6. A large-screen projection-type display using a transmission-type screen, wherein said transmission-type screen is formed of, at least, two sheets, or a front sheet provided on the viewer's side and a Fresnel sheet provided on the projection source side far from said front sheet, both said sheets are tilted toward the viewers by about 0.04 radian or above relative to the vertical direction, said front sheet is tensioned at least in the vertical direction, said Fresnel sheet has a warp of more than about 2.4 times as large as its thickness, and said front sheet and said Fresnel sheet are kept spaced about 7 mm or below. 
     
     
       7. A large-screen projection-type display according to claim 6, wherein said front sheet has spring means provided at its upper and lower ends so that said tension is applied by said spring means. 
     
     
       8. A large-screen projection-type display according to claim 6, wherein said front sheet has a shelf member at least at its lower end so that said tension in said front sheet is applied by exerting the weight of said Fresnel sheet on said shelf member. 
     
     
       9. A large-screen projection-type display according to claim 7, wherein said spring means exerts not only said tension on said front sheet but also a pressure in the horizontal direction thereon. 
     
     
       10. A large-screen projection-type display according to claim 7, wherein said spring means exerts not only said tension on said front sheet but also a pressure on said Fresnel sheet in the vertical direction.